Magnesium has three naturally occurring isotopes (mg-24, mg-25, and mg-26). the atomic mass and natural abundance of mg-24 are 23.9850 amu and 79 %, respectively. the atomic mass and natural abundance of mg-25 are 24.9858 amu and 10 %, respectively. find the natural abundance of mg-26.

The three naturally occurring isotopes of magnesium are: Mg-24, Mg-25 and Mg-26.

The atomic mass and natural abundance of Mg-24 and Mg-25 are 23.9850 amu, 79% and 24.9858 amu, 10% respectively.

Let the abundance of Mg-26 be X thus, sum of natural abundance of all three isotopes will be 100 or,

%Mg-24+%Mg-25+%Mg-26=100

Or,

79%+10%+X=100

or,

X=11%

Therefore, natural abundance of Mg-26 is 11%.